Perfusion computed tomography (CT) imaging (PCT) of the brain is a commonly used modality for assessing damage to brain tissue following events such as strokes. PCT images or maps show the infarcted areas that may be irreversibly damaged and the ischemic area of tissue at risk that might be responsive to rehabilitative therapy (also referred to as the penumbra). Normally perfused tissue areas are also identified.
A number of different perfusion parameters can be determined from the image data produced by the imaging system and used to generate PCT images. These parameters include regional cerebral blood flow (rCBF), cerebral blood volume (CBV), mean transit time (MTT), perfusion weighted imaging (PWI), time-to-peak (TTP) and the delay. Commonly, a radiologist will assess the penumbra and infarcted tissue by reviewing 2D and/or 3D PCT images generated using one or more different perfusion parameters. The radiologist interprets these maps to identify the different brain tissue types. The results of these analyses are then used to select appropriate treatments. For example, an injury characterized by a relatively large infarct core and a comparatively small ischemic region may not be treated using reperfusion therapies. A relatively small infarct region surrounded by a large and salvageable ischemic area, on the other hand, may be a good candidate for these reperfusion therapies.
There remains, however, a continuing need for improved systems and methods for generating reliable perfusion-based tissue viability images. In particular, there is a need for systems and methods that can provide images accurately identifying the classes of the tissue. The ability to quickly provide images of these types would be especially desirable. Enhanced diagnoses and treatments leading to more effective patient outcomes may result.